What it is: Comet C/2024 G3 (ATLAS)
Where it is: In the night sky over Chile, somewhere in the inner solar system
When it was shared: Feb. 12, 2025
Why it's so special: Nicknamed the "Great Comet of 2025," Comet C/2024 G3 (ATLAS) is currently the brightest comet predicted to be visible from Earth all year. Discovered on April 5, 2024 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), it is a nonperiodic comet that's traveling on an orbit that won't bring it back to the sun's neighborhood for hundreds of thousands of years.
Comet C/2024 G3 reached perihelion — the closest point to the sun in its orbit — on Jan. 13, 2025. At this point, it was roughly 8 million miles (13 million kilometers) from the sun, well within Mercury's orbit. That day, the comet's brightness peaked at magnitude -3.8, as reported by the Comet Observation Database (COBS). (In astronomy, a lower magnitude means a brighter object. For comparison, Venus, which is currently visible at night in the ongoing "parade of planets" — has a magnitude of -4.8 right now, according to theskylive.com.) Observers in the Southern Hemisphere could see the Great Comet before and after perihelion, while for Northern Hemisphere viewers, it was visible in the daytime sky only around perihelion.
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Following perihelion, the comet showed signs of disintegration but still put on a dazzling display of bright tails. As it heads toward the edge of the solar system, it will slowly start to fade. And if the comet's remains survive, it's expected to be visible from Earth again in about 600,000 years, according to long-term orbital calculations by the JPL Horizons On-Line Ephemeris System. Recently, according to COBS, the comet's brightness has reduced to greater than magnitude 8, which is considered extremely faint.
This captivating picture shows the once-in-a-lifetime comet as seen over the town of Andacollo, Chile, on Jan. 24, 2025. The comet was beautifully captured by César Briceño, director of the Southern Astrophysical Research Telescope. Briceño used a mirrorless DSLR camera with an 85mm lens at ISO 1600 to get 10 separate images, each exposed for 30 seconds, which were then stacked to create this stunning view.
The image reveals how the comet's appearance has changed due to its proximity to the sun. One of the most noticeable features is the vaporized material of the comet's frozen-solid core, known as the nucleus, which gives the comet a unique shape. As the comet gets close to the sun, it gets warmed up and its icy material transforms from solid to gas. This process creates long tails and an atmosphere around the nucleus, called the coma.
The diffuse coma in the lower-left corner shines brightly, hiding the nucleus. Twin tails are seen emerging from the nucleus. A dust trail made up of heavier dust particles that are lit by reflected sunlight makes up the upper stream of tails. The lower stream is composed of gases that glow from ionization. This tail points in a different direction than the first one because it's influenced by the sun's magnetic field, which makes it line up with the solar wind, the stream of charged particles emanating from the sun.
While faint trails of artificial satellites photobomb the view, the surreal starry backdrop makes the comet truly stand out. Another breathtaking image, which Briceño captured the same night, presents the showstopper against the backdrop of the Chilean mountains near the sea, showcasing a clear sky at dusk.
